The present invention relates to an image forming apparatus.
In a conventional image forming apparatus such as a printer, a copier, and a facsimile, a plurality of image forming units (developing devices) is disposed for attaching toner to a latent image formed on a surface of a photosensitive drum to form a toner image. In the image forming unit, a toner cartridge is detachably attached to a main body of the image forming unit for retaining toner.
A sheet cassette is disposed in the image forming unit for supplying a sheet as a recording medium. A base plate is disposed on guide members arranged at left and right sides of the sheet cassette, and an apparatus main body of the printer is mounted on the base plate.    Patent Reference: Japanese Patent Publication No. 06-211363
In the conventional printer described above, when the printer is provided with a plurality of image forming units, each of the image forming units can be detachably attached to a metal plate structure as a supporting member. It is necessary, however, to provide the guide members and the base plate between a mounting surface for mounting the printer and the metal plate structure. Accordingly, due to dimensional variances of components such as the guide members, the base plate, the metal plate structure, and the likes, it is difficult to precisely mount the image forming units. As a result, a color shift may occur upon forming an image or printing, thereby deteriorating image quality.
In view of the problems described above, an object of the present invention is to provide an image forming apparatus, in which it is possible to solve the problems in the conventional printer. In particular, it is possible to accurately mount an image forming unit and improve image quality.
Further objects and advantages of the invention will be apparent from the following description of the invention.